Sheet metal clamp



Se t. 25, 1951 F. c. WALLACE SHEET METAL CLAMP Filed Jan. 31, 1948 FIG.3.

FIG. 2.

FIG. I.-

FIG. 4.

FIG. 5. FIG. 6'. FIG. 7. FIG.8.

WE T." 5

WA E

CIB

Patented Sept. 25, 1 951 SHEET'METAL CLAMP Frank C. Wallace, NorthHollywood, Calif., as-

signor, by mesne assig Helbush nments, to Herman H.

Application January 31, 1948, Serial No. 5,596

2 clams.

My invention has to do with sheet metal clamps of the type wherein apair of spring-loaded laterally spreadable clamping pins are mounted ina cylindrical body for reciprocal movement through an opening in the endthereof past a stationary spreader mounted between the pins. Such clampsoperate to engage and clamp work sheets between enlarged outer ends ofthe pins and the outer end of the body. My invention also has to do withmethods of making such clamps.

While clamps of this general type are wellknown in the art,difi'iculties have been experienced in assembling them, whichdifliculties have increased the cost thereof, and since in sheet metalwork such as airplane construction such clamps are used by thethousands, any improvement which is conducive to reducing the costthereof is of considerable importance. The assembly difliculties havearisen because of the fact that the interior construction requiresassembly work which can only be done efficiently upon a jig and since,for safety purposes, it has heretofore been considered essential thatthe hole in the outer end of the body be small enough to prevent theenlarged ends of the clamping pins from being retracted into the body bythe spring when the spreader is between them, difficulties have beenexperienced in first making the sub-assembly of the interior parts andsubsequently mounting them in the body.

Another shortcoming of prior art clamps is that they have been of suchconstruction that the enlarged outer ends of the clamping pins projectbelow the outer end of the body even when not being used to clamp worksheets, which exposes them to injury- It is, therefore, an object of mypresent invention to overcome those difficulties by providing a modifiedbody construction and a new method of manufacture;

More particularly I have found that those difliculties may be completelyovercome by utilizing a cylindrical clamp body with an integral outerend wall having a pin-passing opening large enough to permit theenlarged ends of the pins to be fully retracted into the body while thespreader is between them, the internal assembly being then preventedfrom escaping from the opposite end of the body under the influence ofthe spring load by virtue of a peripheral flange on the plunger portionof the internal assembly abutting an internal flange on the body. Thispermits all the internal parts to be set up in a sub-assembly outsidethe body and then inserted in the body through the inner end thereof,after which it is necessary only to peen the body flange into positionto provide an abutment for the plunger flange. ,7

" Still further objects and advantages of my present invention will beapparent from the 01; I

lowing description of a presently preferred em-. bodiment thereof, forwhich purpose I shall refer to the accompanying drawings, in which: Fig.1 is a side elevation; Fig. 2 is a medial longitudinal section with theplunger element shown in elevation and with the clamp in fully retractedposition; Fig. 3 is a view similar to Fig. 2 but showingth clamp inwork-clamping position; Fig. 4 is a section taken on line 4-4 of Fig.3;; Figs. 5, 6, 7, 8, 9 and 10 are side. elevationalg views showing thevarious steps of assembly, the 1 body being shown in section in Figs. 9and 10; and

Fig. 11 is an enlarged perspective view of the, spreader bar. IReferring now to the drawings, the numeral 5''; designates a cylindricalbody which has an annular recess 6 for the reception of an operating;tool, not shown, the outer end wall I presenting; an axial hole 8. Thereis an internal flanged] at-,1: its opposite or inner end of the body.

The internal assembly consists of a pair of re silient laterallyflexible clamping pins I5 having;- right angularly bent inner ends I6and laterals projections or enlargements ll on their outer; ends. Theinner ends of the clamping pins are: held together by a washer I8 andaround the outer end portion of the pins'there is another: washer IS. Acompression spring 20 is held partially compressed between the washersl8 and 19*.

A T-shaped spreader bar 22 (Fig. 11') having a cross portion 22a and acentral outwardly ex-- tending leg 221), has its cross portion 220.inter-Q posed between the outer ends of the clamping,v pins outwardlybeyond the washer I9 while the! central leg 22b projects outwardlybetween thee. pins to a. point beyond the outer ends of said pins.- andthrough the opening in the .body end wall. I

The cross portion 22a of the spreader bar longer than the diameter ofthe hole 8 so thati t; cannot pass outwardly through said hole, and it;also longer than the diameter of the hole in. washer l9 so that itcannot pass upwardly through that hole. The combined thickness of theenlarged outer ends of the clamping pins and the spreader bar betweenthem is greater than, the diameter of the hole in washer I!) so that theouter ends of the pins cannot pass upwardly through the washer l9 whenthe spreader is be tween them. Consequently the spring is confinedbetween washers l8 and I9 and the pins are confined against upward orrearward escapefrom-i the washers by engagement of the enlarged outerends of the pins against washer l9. To actuate the clamping pins toproject their" outer ends through the hole 8 I provide aplunger.25having a peripheral flange 26 on its inner em; This flange providesan upwardly facing sho'ulto subject them; to considerablei abiise wardlythrough the hole in washer l9, tlregpartsJg 1 could not escape throughthe inner en d of thew body because of the abutment of f rlange zs l!)flange 9.

By virtue of the foregoing described construction it is possible andpracticalifto formsa sub?!" .v assembly of the parts l5, l8, I9, and22,-exte U riorly of the body and then to insert theerfti're' bsub-assembly as a unit into the body through the top or inner endthereof by "thfollo" i prdcedure:

"First; the clamping pins are inserted, one at a time, through 'thewashe'r" merger-teen efies eo have been bent at right angles; (Fig? 51.1The sprihg ZWi's nextnlouh'ted aroufhdthe pins and against washer l8(Figffilf Neiitjthle'was 19f is inserted over the outer end's'jofthe'pihs'and' against the spring, after" which" the assembly-is placedbetween jig jeIeme'nts 'A' "and B and the jigis operated tocornpr'esstlrespringfzq as shown in Fig; '7, after which thespreadr-barf" 22 is"'i'nassembly" is then released'from-the"" partsassume the position illustrated in Fig.j8, 1n which'conditio'nthee'ntire sub-assembly, generally denotedby the numeral 30, is reinserted as a unitfinthe'top or inneren the body 5 as'shownin Fig; 91The mang-er 25 is the'ninserted and finally the body is placed-jbetweenthe jigelementsfC' and D): the plunger 7 isfo'rced slightlydnwardly bythe jig el'me C and a peeningt'ool-jE is operated to r a eeii th' top orinner end of the body to iorm*"ain} 40 wardlydisposed'flanged. In thean'dling of sheet metalclamps'it is cornmen for workmenrto iiseftheclamping" purposes other than their intende' tends tofbend distort'jtheprojecting clam iri'gpins so that the clarnps become unusabl I" overcomethis and also malgepossible'the described method 7 off assemblyfl by v1pins to be fully retr ted'intdthe ec amn s o 'inns V r H tectedandconcealed end of the central legjZZfofth'e sp'r d permits theoutererids' of fthefcl i b'press'ed together byftheii engage en Vsidewalls of registering holes mitt s S so that they maybe his ert'ed'through 'h' hol ahead ofgthe leg T2211 of thesp'rea erI' T zzb'brthespreader fi'sjthen insert 'dini'jthf with the bottbm 6nd ofj'thebody tithetopj'worl; sheets; 'Upo crating tool the spring 2U thus're the 91aming pins relative to thespread'e'r "untiltheen larged ends I! engage thebottom 'worl; sheet 'lin the holaihefeilii thus clampin ibjl et ..fiween e endlsg J mi ih' 't I i I with the first-named should 4 body(Fig. 3). To release the clamp the operating tool is again used toproject the pins outwardly of the body until the enlarged ends ll arefar enough beyond the outer end of the spreader bar topermit the pins tobe withdrawn from the regis tering holes in the work sheets.

"""I claim:

lfrhe rnethod of making sheet metal clamps from a collectionpf partsincluding a pair of flexible'fclampingpins each having a lateralprojection altea ego, a pair of Washers, a compression spring, T shapedspreader and a peripherally,flangejdwplunger, which method comprises forming a sub-assembly of the pins, washers,"sp'ring and spreader byinserting the pins in one of the washers, applying the spring around thepins with its inner end abutting "said er, applying the'otherwasheraround the "pins and against the outer end of the spring, partiallycompressing the spring and inserting the sp'read er between the outerends of the pins below the last applied washer so that the cross portionof the spreader projects laterall from between the pins, providing acylindrical body having an'end' Wall presenting an axial opening of "adiameter" greater than the combined'thickness of the spreader and theouter ends of the pins with their lateral projections and'jtheninsertingsaid sub-assembly axiallyj outer end first; into the 71 bodythrough the inner end thereof, inserting the 'j plunger through theinner endofjthe body into engagement with the inner ends of the pinsand" peening the inner end of the body inwardly 'suffi ciently tooverhang the flange on the plungeii v 2. A sheet metal clamp comprisinga tubular' body having anbuterend closure'withan "axial"; 1 openingtherethrough and having an inwardly facing shoulder at its inner end; apair of flexible clamping legs'mou'nted' in'thebody for protrac' i tionand retraction through said openingg 'said; legs haying enlarged outerems; a spring-"infi ld body urging thelegsaxiallytinwa operatingplunger" mounted in from the inner end of; he body, said ing aflangedjinnerend disposed it b g} a rigid spre 11* be e spreader memberand said legs being lengthin'relation to the lengtho'f thebcd tr "ANdive he REFERENCES :CITEII The following references are of record in thef

